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Over much of the 20th century, utilities, regulators and customers each relied upon lab and field meter testing efforts which were primarily focused upon the accuracy of the watt-hour meter and demand register.

This focus is now changing with overwhelming deployment of electronic meters and significant deployment of AMR and AMI meters throughout the installed base in North America.

The focus has now shifted to the metering installation as a whole and not the accuracy of the meter.

2.
Premise
• Over much of the 20th century, utilities, regulators and customers each
relied upon lab and field meter testing efforts which were primarily focused
upon the accuracy of the watt-hour meter and demand register.
• This focus is now changing with overwhelming deployment of electronic
meters and significant deployment of AMR and AMI meters throughout the
installed base in North America.
• The focus has now shifted to the metering installation as a whole and not
the accuracy of the meter.

3.
Field Testing
Common Features and Common Sources of Concern
Electro Mechanical meters were
subject to registration errors caused
by mechanical issues with moving
parts resulting in either the loss of
revenue to the utility or over billing
for the customer. Some of the more
common problems were:
•
•
•
•
Friction wear
Gear mesh misalignment
Retarding magnet failure
Timing motors

4.
Electronic Meters – new failure modes require new testing
and inspection methods
Electronic meters fail as do electro mechanical meters but differently
• Their overall life expectancy is not nearly the same
• Failure modes include drift (unexpected)
• Failure modes include catastrophic (expected)
• Failure modes include non-catastrophic but significant measurement error
modes
• Failure modes can include non-measurement issues which render the meter
ineffective or inaccurate for billing purposes.

5.
Traditional Non-Meter Related problems
Any metering site has always had a number of issues that could also cause metering inaccuracies,
billing inaccuracies, safety concerns or some combination of all three.
Residential metering sites;
•
Traditionally utilities trained their meter readers to look for any abnormal conditions that might
reflect a failing or failed meter, cut seals, tampering, or a dangerous condition. Some meter
readers were better than others, but most were excellent lines of defense against bad metering
and unsafe conditions.
•
Second line of traditional defense were trouble calls to the residence.
•
In an AMI environment we are going to have to rely on trouble calls, information gleaned from the
data gathered (or not gathered) and the Random Sample program used by the utility – regardless
of whether the testing is being done in the shop or the field.

6.
Traditional Non-Meter Related problems (cont)
Issues at Transformer Rated sites;
•
The monthly meter read and if there was a demand, the demand reset allowed the
utility to see these sites every month.
•
The resources used for this are traditionally better trained and more likely to note an
issue.
•
Utilities also tended to have an annual or periodic inspection program already in
place.
•
As personnel cut backs became rampant in the industry many of these programs were
cut back (less frequent) or eliminated, or just chronically behind.

8.
Data Base, Protocols, and Field Tool for
Performing these checks
•
•
•
•
•
•
•
•
•
Data Base tool must be able to record all data from the field.
This tool must be easy to use with a variety of platforms
This tool must be updateable by meter operations
Site verification protocols should be a living set of documents
Different protocols should be developed for different types of meters and
different types of metering sites.
All data about the site should be available for the operator in the field
All new data should be recorded without over writing pre-existing data (as
expected, as found, as left)
Protocols should also be check lists. Pull down menus are preferred
Data can come back to system of record either live or in batch mode

9.
Potential Site Check List
• Verify the meter number
• Record the GPS location of the site or verify the location
• Take a picture of the site
• Verify Access information and add any new information as
required
• Verify protocol to be used for this site

12.
Potential Site Check List (cont)
• Visually inspect for energy diversions (intentional
and not). This includes broken or missing wires,
jumpers, open test switch, unconnected wires and
foreign objects on meters or other metering
equipment. Broken or missing wires can seriously
cause the under measurement of energy. A simple
broken wire on a CT or VT can cause the loss of 1/3
to 1/2 of the registration on either 3 element or 2
element metering, respectively.

13.
Potential Site Check List (cont)
• Perform and record the test result
• Visually check lightning arrestors and transformers for
damage or leaks.
• Check for proper grounding and bonding of metering
equipment. Poor grounding and bonding practices may
result in inaccurate measurements that go undetected
for long periods of time. Implementing a single point
ground policy and practice can reduce or eliminate this
type of issue.

14.
Potential Site Check List (cont)
• Verify service voltage. Stuck regulator or seasonal capacitor can impact service voltage.
• Verify condition of metering control wire. This includes looking for cracks in insulation, broken wires,
loose connections, etc.
• Compare the test switch wiring with the wiring at the CTs and VTs. Verify CTs and VTs not cross
wired. Be sure CTs are grounded in one location (test switch) only.
• Check for bad test switch by examining voltage at the top and bottom of the switch. Also verify
amps using amp probe on both sides of the test switch. Verify neutral connection to cabinet
(voltage).
• Check rotation by closing in one phase at a time at the test switch and observing the phase meter
for forward rotation. If forward rotation is not observed measurements may be significantly impacted
as the phases are most likely cancelling each other out.
• Test meter for accuracy. Verify demand if applicable with observed load. If meter is performing
compensation (line and/or transformer losses) the compensation should be verified either through
direct testing at the is generally a very small percentage of
• Loss compensation site or by examining recorded pulse data.
the overall measurement and would not be caught under
utilities normal high/low checks. However, the small
percentages when applied to large loads or generation can
really add up over time. Billing adjustments can easily be in
the $million range if not caught early.

15.
Potential Site Check List (cont)
•
Verify metering vectors. Traditionally this has been done using instruments such as a circuit
analyzer. Many solid state meters today can provide vector diagrams along with volt/amp/pf and
values using meter manufacturer software or meter displays. Many of these desired values are
programmed into the meters Alternate/Utility display. Examining these values can provide much
information about the metering integrity. It may also assist in determining if unbalanced loads are
present and if CTs are sized properly. The vendor software generally has the ability to capture
both diagnostic and vector information electronically. These electronic records should be kept in
the meter shop for future comparisons.
•
If metering is providing pulses/EOI pulse to customers, SCADA systems or other meters for
totalization they also should be verified vs. the known load on the meter.
•
Verify meter information including meter multiplier (rework it), serial number, dials/decimals, Mp,
Ke, Primary Kh, Kr and Rate. Errors in this type of information can also cause a adverse impact
on measured/reported values.
•
Verify CT shunts are all opened.

16.
Potential Site Check List (cont)
• Burden test CTs and voltage check PTs.
• Ratio Test the CT’s and PT’s
• Record results. Review previous results and perform a
review all the way back through the billing.

19.
Questions and Discussion
Tom Lawton
TESCO – The Eastern Specialty Company
Bristol, PA
215-688-0298 (cell)
1-800-762-8211
This presentation can also be found under Meter
Conferences and Schools on the TESCO web site:
www.tesco-advent.com